I know the basic differences between my 1975 K5's frame and A 1990 K5's frame. It looks like the body mount behind the door is located on outriggers on the 1990 and is inside the frame on a crossmember for my 75. Was any thing else changed that I should Know about? At the local salvage yard I found a brand new GM frame for a K5. No rust, no pits, Gm black paint, and GM partnumber tags all over it. Its sitting under a 1990 K5 with no body mounts installed yet, no front end and no rear bed floor, so I can see the hole frame. Nothing is bolted on. I was told the truck was hit hard in the front and needed a new frame but was sent to the yard due to lack of funds to fix. For 200.00 I can have a brand new GM K5 frame never installed for my 1975. What do you think?